8 they 'are' near the great stone that 'is' in Gibeon, and Amasa hath gone before them, and Joab 'is' girded; his long robe he hath put on him, and upon it a girdle—a sword 'is' fastened upon his loins in its sheath; and he hath gone out, and it falleth.
Matthew Henry's Commentary on 2 Samuel 20:8
Commentary on 2 Samuel 20:4-13
(Read 2 Samuel 20:4-13)
Joab barbarously murdered Amasa. The more plot there is in a sin, the worse it is. Joab contentedly sacrificed the interest both of the king and the kingdom to his personal revenge. But one would wonder with what face a murderer could pursue a traitor; and how, under such a load of guilt, he had courage to enter upon danger: his conscience was seared.